Speaker
Description
In hadronic collisions, heavy-flavour quarks (beauty and charm) are produced in hard-scattering processes with large momentum transfer. The production of hadrons containing beauty quarks provides a very important test of perturbative QCD calculations in pp collisions. Measurement of beauty-hadron production in heavy-ion collisions is a unique tool to investigate the properties of the colour-deconfined medium created, the quark--gluon plasma (QGP). Beauty quarks are effective probes of the QGP, as they are created via initial hard partonic scatterings and subsequently experience the full evolution of the QGP medium. In addition, beauty quarks, being four times heavier than charm quarks, can be exploited to study the mass dependence of the in-medium energy loss. Beauty production measurements in proton-nucleus collisions are useful to understand cold nuclear matter effects.
In ALICE beauty production is investigated through different decay channels, one of them makes use of J/$\psi$ coming from the weak decays of beauty hadrons. The inclusive J/$\psi$ yield is composed of two contributions: prompt J/$\psi$ produced directly in the collision or indirectly via the decay of heavier charmonium states, and non-prompt J/$\psi$ originating from the decays of beauty hadrons. The latter are displaced from the main event vertex by an average distance of about 500 $\mu$m. Thanks to the excellent resolution on the reconstructed impact parameter (defined as the Distance of Closest Approach of the corresponding trajectory of the track to the primary vertex) provided by the Inner Tracking System,
it is possible to measure such non-prompt J/$\psi$ fraction and disentangle the two contributions.
In this presentation the beauty production measurements through the non-prompt J/$\psi$ decay channel in pp and Pb-Pb collisions measured by the ALICE collaboration at the LHC will be discussed.
